Outlook 2010 and 2013 - warning about changing location for mail delviery

When you have multiple email addresses, and using POP or IMAP, the trend in the newer Outlook is to create individual PST files for each email address. If you later decide you want email delivered to you "main Outlook Inbox, say in your main pst file, then when you change it be warned.  You are not just directing that future new email is to be delivered there.  But if you have the Advanced Setting for an accounting (in Account Settings) so that a certain number of days (14?) left up on the sever...when you set the new Inbox to receive email, Outlook will fetch the entire trove of server stored emails.